From cb37617687f2bfa5b675df7779f869147c9002bd Mon Sep 17 00:00:00 2001

From: Zeng Heng <zengheng4@huawei.com>

Date: Sat, 3 Dec 2022 15:34:41 +0800

Subject: [PATCH] net: mdio: fix unbalanced fwnode reference count in mdio_device_release()

Git-commit: cb37617687f2bfa5b675df7779f869147c9002bd

Patch-mainline: v6.1

References: git-fixes

There is warning report about of_node refcount leak

while probing mdio device:

Of: ERROR: memory leak, expected refcount 1 instead of 2,

of_node_get()/of_node_put() unbalanced - destroy cset entry:

attach overlay node /spi/soc@0/mdio@710700c0/ethernet@4

In of_mdiobus_register_device(), we increase fwnode refcount

by fwnode_handle_get() before associating the of_node with

mdio device, but it has never been decreased in normal path.

Since that, in mdio_device_release(), it needs to call

fwnode_handle_put() in addition instead of calling kfree()

directly.

After above, just calling mdio_device_free() in the error handle

path of of_mdiobus_register_device() is enough to keep the

refcount balanced.

Fixes: a9049e0c513c ("mdio: Add support for mdio drivers.")

Signed-off-by: Zeng Heng <zengheng4@huawei.com>

Reviewed-by: Yang Yingliang <yangyingliang@huawei.com>

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Link: https://lore.kernel.org/r/20221203073441.3885317-1-zengheng4@huawei.com

Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/net/mdio/of_mdio.c    | 3 ++-

 drivers/net/phy/mdio_device.c | 2 ++

 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mdio/of_mdio.c b/drivers/net/mdio/of_mdio.c

index 796e9c7857d0..510822d6d0d9 100644

--- a/drivers/net/mdio/of_mdio.c

+++ b/drivers/net/mdio/of_mdio.c

@@ -68,8 +68,9 @@ static int of_mdiobus_register_device(struct mii_bus *mdio,

 	/* All data is now stored in the mdiodev struct; register it. */

 	rc = mdio_device_register(mdiodev);

 	if (rc) {

+		device_set_node(&mdiodev->dev, NULL);

+		fwnode_handle_put(fwnode);

 		mdio_device_free(mdiodev);

-		of_node_put(child);

 		return rc;

 	}

diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c

index 250742ffdfd9..044828d081d2 100644

--- a/drivers/net/phy/mdio_device.c

+++ b/drivers/net/phy/mdio_device.c

@@ -21,6 +21,7 @@

 #include <linux/slab.h>

 #include <linux/string.h>

 #include <linux/unistd.h>

+#include <linux/property.h>

 void mdio_device_free(struct mdio_device *mdiodev)

 {

@@ -30,6 +31,7 @@ EXPORT_SYMBOL(mdio_device_free);

 static void mdio_device_release(struct device *dev)

 {

+	fwnode_handle_put(dev->fwnode);

 	kfree(to_mdio_device(dev));

 }

-- 

2.35.3